The invention described herein relates to the field of military packaging requirements and materials for the transportation, handling, and storage of 81 mm and 120 mm Mortar ammunition. Specifically, the present invention relates to fiber ammunition containers employed as the primary means of protection and preservation of the cartridges from the environmental extremes and rough handling scenarios encountered by ammunition throughout its logistic lifecycle.
All weapons, ammunition, fire control equipment, vehicles, and sustainability hardware used in military war and peace-time applications are subject to high standards of packaging, transportation, and handling governed by MIL-STD-2073-1, MIL-STD-1904 and MIL-STD-1905, as well the Department of Transportation authored CFR 49. Exemplary cases are relatively lightweight, mobile weapons such as the U.S. Army""s 81 mm and 120 mm mortars. The inherent portability, flexibility and ubiquity of these weapons dictate that they and the ammunition they fire will be exposed to a very wide range of non-ideal conditions. In particular, these weapons and their ammunition are expected to perform as designed in conditions that include extreme heat and cold, as well as wet and dusty environs. In addition, ammunition for these mortars is expected to survive high g-loadings such as those that might be experienced when being transported by tracked or wheeled vehicles, carried by soldiers, or delivered by a fixed-wing or a rotary-wing aircraft.
For protection, individual rounds of ammunition for mortars and other large caliber weapons are packaged in individual fiber containers. In addition to this primary packaging method, this protection may be augmented by secondary packaging in metal cans or wooden boxes. However, it may be appreciated that in many circumstances the ammunition must survive without the benefits of secondary packaging, that is, with the only packaging and protection being afforded by the primary container. This is particularly true when the ammunition is transported by soldiers or by vehicles with limited carrying capacity, wherein key considerations are bulk and mass. Specifically, the rounds must survive the non-ideal conditions but the packing must be minimized.
Over the past years primarily asphalt-impregnated fiber ammunition containers specified by MIL-C-2439 have protected mortar rounds in the field. These containers adequately address the transportation, storage and handling issues however asphalt has been highlighted as a substance that is hazardous to the environment. In answer to this, manufacturers who normally use asphalt in their processes have come to develop material replacements. Increased regulatory measures concerning the disposal and use of asphalt has resulted in a decrease in suppliers and an increase in cost. Moreover, xe2x80x9chandling hazardsxe2x80x9d in the container production process, such as the fumes and burns from the asphalt which must be stabilized at a high temperature to maintain the flow, are cause for health-safety concerns and cost increases.
A possible alternative to the asphalt container is the use of the Type IV, wax-impregnated version of MIL-C-2439. Again, however, although this option would resolve the environmental issues, the production issues remain (Manufacturers are subject to high temperature baths of molten wax.) and performance issues are introduced. In the field, the wax-impregnated containers are plagued by distorted or illegible markings. The containers also leave a sticky residue on the user""s hands and the ammunition when temperatures exceed the softening point of the wax (approximately 100xc2x0 Fahrenheit). The wax resin also significantly weakens the adhesion strength between the container inner tube and the outer tube. As a result, the container""s structural strength and integrity are compromised by the wax-dipping process.
Consequently, to date, there is no effective means of producing a high-performance, cost-effective, worker-safe, and environmentally sound container for mortar rounds.
A feature of the present invention is to provide a polyethylene-laminated fiber container that addresses the foregoing concerns. This container allows the manufacturer to produce a fiber tube in a low-temperature, clean-air environment, and ultimately equips the user with a low-cost, highly- durable, water-vapor tight, and light-weight means of transporting and protecting ammunition.
Briefly, the container is a spiral-wound, laminated cylinder capable of protecting a mortar or other round from a large number of environmental conditions. The laminate material, known by the generic name xe2x80x9cPolyLamxe2x80x9d includes a layer of low-density polyethylene (LDPE) heat-bonded to a kraft paper. The laminate material is both strong and moisture-resistant. During the cylinder manufacturing process, multiple layers of this laminate material, augmented by one or more layers of aluminum foil, are wound in a spiral fashion over an interior cylinder of ammunition container board, using conventional tooling and machinery. Layers of the cylinder are bonded to their contiguous neighbors by adhesive. The ends of the containers are sealed with crimped metal end caps, effecting a durable and moisture-resistance seal and giving the cylinder added crush-resistance. The construction of the containers requires no high temperature operations, produces no noxious fumes, and does not expose workers to hazardous or toxic materials. In addition, there is less waste as compared to the current technology.
Once a round of ammunition is placed in the interior of the fiber container, it is sealed with a pressure sensitive tape, rendering it both easily opened and re-sealed, even under battlefield conditions. The design of the tube allows the fins of the encased mortar round to be grasped for easy removal. In addition, the surface of the container is easily gripped to prevent slippage on the part of the user.
The fiber container of the present invention is used as the primary packaging for individual rounds. While the fiber container will be described herein in connection with mortar ammunition, it is readily adapted to tank ammunition, grenades, and other ammunition families that utilize the fiber or similar container packaging technology.
Each round variation (e.g., 81 mm High-Explosive Cartridges, 81 mm Illuminating Cartridges, 120 mm high-Explosive Cartridges, etc.) has an associated packing and marking drawing for the loading and closure of the ammunition container. There are specially designed fuze supports and cushioning systems for each cartridge that become an integral part of the ammunition tube and, thus, provide superior protection for the mortar round.
Secondary containment of ammunition is used where practicable. Over-packs are generally metal for the combat ammunition and wood for the training ammunition. With a metal over-pack the fiber container is capable of meeting its specifications for a range of temperatures between approximately xe2x88x9265xc2x0 F. to +160xc2x0 F. The improved water-vapor resistance of the PolyLam is especially valuable in the case of the training ammunition, as the wood over-pack leaves the ammunition containers much more vulnerable to the elements than the metal cans.